The invention concerns a drive and dosing device for an injection device for administration or discharge of a liquid product, in particular a medication, for example insulin for diabetes treatment. In particular, the invention also concerns an injection device that has such a drive and dosing device.
The term “medication” here comprises any flowable medicinal formulation that is suitable for controlled administration through a means like a cannula or hollow needle, for example a liquid, a solution, a gel, or a fine suspension that contains one or more medicinal agents. “Medication” can be a composition having a single active agent or a premixed or co-formulated composition having a plurality of active agents in a single container. “Medication” comprises drugs like peptides (for example, insulins, insulin-containing medications, GLP-1-containing as well as derivative or analogous preparations), proteins and hormones, biologically obtained or active agents, agents based on hormones or genes, nutrient formulations, enzymes, and other substances both in solid (suspended) or liquid form, and also polysaccharides, vaccines, DNA or RNA, or oligonucleotides, antibodies or parts of antibodies, as well as suitable basic agents, auxiliary substances, and vehicles.
An injection device having a dose display drum and a drive spring is known from the prior art, for example WO 2008/031237 A1. The drive spring is a clock spring, which is wound in a spiral from a strip material. In the selection of the desired product dose, the spring is tensioned with a rotary motion. To discharge the dose, a piston rod of the device is coupled to the spring by actuation of an actuation button at the proximal end of the device, whereby the spring can transmit the energy stored in it to the piston rod, due to which the piston rod is moved in the discharge direction. To select a new dose, the spring is again tensioned by rotating the dosing button. This is repeated until the product container is empty.
An injection device with a coil spring is known from U.S. Pat. No. 5,104,380 A, the coil spring being likewise tensioned by rotation during dose selection, so that the coil spring can be called a torsion spring. The spring, which is tensioned before each product discharge by rotation of a rotatable button, transmits its energy to the piston rod in order to drive it.
EP 2 644 217 A1 describes an injection device with a dose display and a spring drive, where a spring that has been pretensioned in the delivered state of the device and that acts between an advancing member and an abutment has been pretensioned with enough energy that it can discharge the maximum amount of product that can be discharged from the product container in a plurality of individual discharges.